Damper control for stokers



April 16, 1935. J. ROLAND i DAMPER CONTROL FOR STOKERS Filed March 2,1933 2 Sheets-Sheet 1 f. ---nun IN VEN TOR ATTORNEYS.

April 16, 1935. J, ROLAND l 1,997,833

DAMPER CONTROL FOR STOKERS Filed March 2, 1935 Sheets-Sheet 2 INVENTORJaw/V KOL fir/v0.

ATTORNEYI Patented Apr. 16, 1935 UNITED STATES PATENT OFFICESchwuler-Cummins Company,

Ind., a corporation Indianapolis,

Application March 2, 1933, Serial No. 659,321 3 Claims. (Cl. 137-153)This invention relates to an automatic damper control,` particularlyadapted for use with furnace stokers and the like.

In connection with the usual furnace stokers there is a motor-drivenfanwhich produces a forced draft through an air conduit leading to the iirepot, which fan usually operates during all or a portion of the time thatthe fuel is being mechanicallyfed therein. Also during non-feeding ofthe fuel there is a natural draft through such conduit which facilitatesthe burning of the fuel. As a result thereof, the fuel may be toorapidly consumed under certain conditions. During mild temperatures whenthe fuel is intermittently fed during short periods of time, so as tomaintain a low or kindling fire in the me pot, an excessive amount ofair is forced therethrough, which quickly consumes the fuel. In additionthereto, and during the non-feeding periods, the natural draft continuesto consume the fuel more rapidly than required. This sometimes resultsin the fire being burned out between the time of the last feeding andthe next feeding of fuel. 'Ihe furnace then becomes dead and must berekindIed in addition to quantities of unburned fuel being fed into thei'lre pot.

It is the object of this invention to automatically control both theforced and natural drafts in accordance with heat requirements and thecharacter of the fuel bed in the fire p'ot. The ultimate object oftheautomatic control is principally to retard consumption of the fuelduring non-feeding periods to maintain a kindling or pilot flre in thefurnace overr a longer period of time when there is no heat requirement.'I'his is accomplished by not only cutting down the forced draft duringthe feeding for kindling maintenance, but by closing the natural draftduring the intervals between feedings.

The above is accomplished by' providing a butterfly type of valve in theair conduit which normally is in closed position, but which may be movedto open position or partially open posi--l tion by static pressurecreated in the conduit. Thus, during substantial periods of heatrequirement when the fuel is continuously fed to the fire box andthereby becomes packed therein, and it is desirable to produce themaximum forced draft, the current of air delivered by -the fan strikesthe' compact bed of fuel and thereby raises the static pressure in theconduit, resulting in the valve being opened so as to permit the maximumair ow to the fuel. When there is little or no fuel being fed into thefire bed, the air passage through the bed is more open so that thecurrent of air freely passes therethrough, reducing the static pressurein the conduit, which results in the valve being wholly or partiallyclosed to cut off the air supply and, therefore, prevent the fuel frombeing too rapidly burned.

This is accomplished by providing a pressureactuated member connectedwith the valve and mounted on the air conduit for moving said valve toits 'maximum open position when the pressure thereon is increased andpermitting said valve to approach closed position as the pressure isdecreased.

Ihe full nature of the invention will be understood from theaccompanying drawings and the following description and claims:

In the drawings Fig. 1 is a diagrammatic illustration of a furnaceshowing a fire pot and draft conduit with a valve control mountedthereon. Fig. 2 is a sectional view through a portion of thedraftfconduit and valve control showing the valve in open position. Fig.3 is the same as Fig. 2 with parts removed, showing the valve in closedposition. Fig. 4 is a section on the line 4-4 of Fig. 2. Fig. 5 is acentral vertical section through a modified form of valve control shownin open and fully operative position. Fig. 6 is a section taken on theline 6-6 of Fig. 5, with the parts in partially operative position.

In the drawings there is illustrated a furnace I having the usual firepot II containing a bed of fuel I2, the fuel beingforced therein by anunderv feed stoker of the usual type from the fuel hopper I3. The fuelfeed I3ay and the forced draft are operated from the usual electricmotor I4. Driven by the motor I4 there' is a centrifugal fan I containedwithin a fan housing I6 connected with an air conduit I1 leading to there pot I I for delivering thereto air by forced or natural draft.

Mounted within the air conduit I1 there is a draft control including aframe I8 adapted to extend into and lie adjacent the walls of theconduit. Pivotally mounted on said frame there is a. valve I9 formed ofa plate of substantially the form as the cross sectional area of theconduit, said plate being provided with slightly bent end portionsand-2l. On one side of said plate therel is a dependent counterweight22, and on the other side thereof there is a bracket 23 to r which acontrol rod 21 is loosely connected. The frame I8 is secured to andsupported by a housing 28. Said housing is mounted over an opening 29`formed in the top of the conduit, through which opening the frame I8and rod 28 extend.

The housing is provided with a saddle 30 by which it is secured over theconduit in fixed relation. to the slowest possible burning of the fuel,where- Closing the lower end of the housing 28 and .by the danger of itsbeing consumed and the fire: sealed therein there is anupwardly-extending extinguished between operations of the stoker willthimble 3| which acts as a guide for the rod 21, be eliminated.

5 the walls of the thimble being spaced from the By slightly bending theends of the valve plate, 5

walls of the housing. The rod 21 extends freely indicated at 20 and 2|,the automatic action of through an aperture 32 in the dome-shaped topthe valve is facilitated. This is also assisted of the thimble to permitair to freely pass through through the medium of the counterbalanceweight the top thereof. Mounted over and about the 22. Furthermore, astop member, such as is inthimble there is a plunger or cup 33 providedwith dicated at 43, may be mounted upon the frame lo a dome 34 adaptedto'flt over the dome-like top I8 to limit the swinging action of thevalve to of the thimble 3|. The sides of the cup extend open position,its swinging action to closed posiwell down between the thimble andhousing and tion being limited by engagement with the bottom the edge ofthe open bottom thereof is immersed and" top of the frame. 4

in a bath of oil, indicated at 35. The oil level Pivotally mounted overthe top of the housing l5 which at all times extends above the bottom of28 there isv an adjusting rod 4| having a handle the cup is maintainedby the filler inlet 36. The 42 movable to variouspositions in respect toa cup 33 is provided with a vent opening 31 in the plate v43. Said rodis provided with a U-shaped upper portion thereof. The rod 21 extendsend 44 which, when moved'` to its upper position,

through the top of said cup and is sealed thereto as illustrated in Fig.42, will limit the downward 2o so as to be air tight. Said rod alsoextends freely movement of the rod 21 and,` therefore, prevent throughan aperture 33 in the top of the housing the full closing of the valve.When/it/is'" moved and is provided on the upper free end thereof with tothe extreme lower posit shown in Fig. 3, an indicator button 39. it willpermit the op of the rod and com- 25 In operation, assuming that thefuel I2 is tightplete clos' gpfie valve. g5 ly packed in the fire potand is being contin- Irl/tlrlodined form of vulve control mueuously fedtherein under heat requirement con.- rated in Figs. 5'an'd 6, the valveIII is provided ditions, the resistance to the passage of r with aslightly bent end |2| and a bracket |23 is through the fuel will createa relatively high static connected to the plunger or disk |33 by acontrol 3p pressure in the conduit I1. This will cause air. rod |21. Theplunger |33 conforms substantially 3p to be forced into the thimble 3|and through the to the cross sectional area of the housing |23 aperture32 into the cup 33, creating the same so as to move upwardly thereinunder air prespressure therein. The air not being able to essure anddownwardly by gravity. Rotatably cape from the cup by reason of the oilseal, will mounted over the closed upper end of thev housing 35 tend toraise said cup in order to increase the |28l there is arotatablyadjustable control cap |33 35 capacity thereof. Upon the cup beingforced uphaving downwardly extending flanges |44 closely wardly by theair pressure, the stem 21 will be fitting thel upper side walls of thehousing and carried therewith to raise that portion of the provided withaplurality of apertures I4| adapted valve to which it is connected,whereupon the to be moved in and out of registry with the apervalve willbe moved toward or into its open poitures |42 formed in the housing.Secured on thel 40 s itlon, as illustrated in Figs. 2 and4. Thus, theouter side of the housing, there is a corrugated draft conduit I1 willbe free of obstruction by the plate |43 against which anl adjustablehand lever valve. |44 engages for setting a control adjustment rod Whenthe heat requirement decreases and rel- |45 which extends diametricallythrough the 45 atively little fuel is fed or packed into the fuelhousing so as to be rotatably supported therein. 45 bed, there will beless resistance to the flow of Said control rod is provided with aU-shaped air through the fuel so that the static pressure bend |46intermediate the sides of the housing in the conduit will drop and nolonger tend to and passing about the rod |21. raise-the cup 33 and openthe valve. The drop This type of controloperates-upon the same 50 instatic pressure will permit the cup 33 to drop principle and for thesame purpose as the type 50 by gravity so as to tend to close the valve.The previously described, excepting that the resistposition of the valvewill .thereupon be balanced ance to its upward or opening movement may.be

at 0r near closed position, depending upon variavaried and adjusted byrotation of the cap |33 tion of the static pressure, which in turn willdeto vary the extent of registry of the apertures pend on thevariationof resistance -to the pas- |4| and |42, when geld apertures ereclosed, 55

Sage 0f air through the fuel bed. .assuming there can be no air leakagethere- Thus 1t Win' be undelStOOd that the quantity 0f through, thevalve is inoperative, since the static all' driven through the f llelbed by the fan, Or fan pressure will be 'the same on both gldeg 0f thecapacity, will be automatically maintained subplunger |33, However, withthe apertures open stantially constant irrespective of variations in orpartially opemeo. that )he muy escupe 60 the resistance t0 its passageCreated by the packtherethrough, there will be a differential pressure,ing of the fuel, since a balance is maintained bewhereby the pressure onthe underside of the tweenthe resistance of the fan and fuel, i. e.,plunger may be greater than on the upper side as the fuel resistanceincreases, the valve reso4 as to raise the plunger and open the valve.

sistance decreases and vice versa. However, when the static pressure inthe con- 65 vWhen no heat is required and the/Stoker is dull; l1 dropsto atmospheric pressure, then there merely operated to maintain akindling or pilot will be en equelizlng of pressure such es to perre,the passage of air will be so'freely permitted mlt the plunger to dropby gravity and close the through the fuel bed as to eliminate 4anystatic valve By adjusting the registry 0f the ape!- pressure in theconduit so that the cup 33 will tures, a greater or less Statie pressurelmuy be 70 drop to closed position, as Shown in Fig. 3, required to openthe valve, as will be.. clearly whereupon the valve will be completelyclosed understood from the ebove l and substantially cut olf both theforced draft By moving the rod |45 about its pivotalmountand naturaldraft. This substantial elimination ing, the U-shaped portion |43 mayberaised or of either forced or natural draft will be conducive loweredinto or outv of the way ofthe plunger.

Thus, by moving it to its extreme upper position, Y

the plunger will be restricted in its downward movement so that thevalve will at no time be entirely closed, but remain partially open. Theextent of the closing of the valve may, therefore, be varied, dependingupon the position of the rod, its lower position being such as topermitthe full drop of the plunger and the full closing of the valve.

'Ihe invention claimed is:

1. A draft regulator comprising a butterfly valve pivotally mountedwithin a conduit for partially closing said conduit when swung to oneposition and substantially opening said conduit when swung to anotherposition, a housing open to said conduit, a plunger iloating in saidhousing andv operatively connected with said valve,4

said plunger and valve being so positioned with respect to said conduitas to cause said plunger to be lifted by an increase in pressure in saidconduit to move said valve to open position and lowered by gravity upona decrease in said pressure to move said valve to partially closedposition, and adjustable means for effecting a resistance to themovement of said plunger and valve toward open position.

2. A draft regulator comprising a butterfly valve pivotally mountedwithinV a conduit for partially closing said conduit when swung to oneposition and substantially opening said conduit when swung to anotherposition, a housing open to saidconduit, a plunger oating in saidhousing and operatively connected with said valve,

said plunger and valve being so positioned with respect to said conduitas to cause said plunger to be lifted by an increase in pressure in saidconduit to move said valve to open position and lowered by gravity upona decrease in said pressure to move said valve to partially closedposition, said housing having an aperture therein, and a control cap forvarying the area of said opening to control the resistance to thelifting movement of said plunger.

3. A draft regulator for a draft conduit comprising a butterfly valvepivotally mounted intermediate its ends within said conduit so as topartially close said conduit when moved to a vertical position and openthe passage thereto when moved to a substantially horizontal position, ahousing in communication with said conduit adjacent said valve, aplunger reciprocable within said housing, a connecting rod connectingsaid plunger and valve and so arranged with respect thereto as to swingsaid valve to substantially a horizontal position when said plunger isforced upwardly by pressure in the conduit and permit said valve toswing to substantially a verjtical position by gravity upon decrease inpressure, said housing having an aperture therein, and a control cappivotally mounted on said housing for varying the effective area of theaperture therein for varying the effective pressure upon said plungerexerted from within said conduit and housing.

. JOHN ROLAND.

